1. Field of the Invention
The present invention generally relates to frequency discriminating circuits and, more particularly, is directed to a frequency discriminating circuit for use in a display device which displays image signals of a plurality of signal formats.
2. Description of the Prior Art
Image signals from computers, for example, have a variety of formats in which the horizontal synchronizing frequencies thereof are 47 kHz or 63 kHz. Accordingly, in a display device which displays image signals of plurality of signal formats, circuits within the display device must be switched in response to the horizontal synchronizing frequency of the input signal, otherwise the synchronization of the picture is disordered and a picture cannot be displayed satisfactorily.
To remove the above-mentioned disadvantage, the conventional display device is provided with a manual switch, for example, and the user switches this manual switch in response to the horizontal synchronizing frequency of the input signal in a manual fashion. This method in which the user switches the manual switch in a manual fashion, however, forces the user to do extra work. Particularly when computers having a variety of formats are switched in use, the work becomes complex. Further, if the user forgets the switching of the computers, there is then the risk that the user will misunderstand this state as a fault or the like.